Fluorescence image acquisition apparatus and imaging system comprising such an apparatus

ABSTRACT

The invention concerns an image acquisition apparatus comprising a UV radiation source ( 29 ) capable of making fluorescent supports ( 1 ) whereof the images are to be acquired, a window ( 21 ) transparent to UV and visible light, typically rectangular, for receiving an image support to be acquired, a linear sensor ( 31 ) whereof the length is preferably substantially equal to the width of the window receiving a support and means ( 23 ) driving the sensor and, preferably the UV radiation source parallel to one of the edges of the window ( 21 ) receiving an image support. The invention is mainly applicable to image acquisition for revealing a chemical or physical phenomenon. The invention is mainly applicable to planar chromatography or layer chromatography.

The present invention relates mainly to a fluorescence image acquisitionapparatus and to an imaging system comprising such an apparatus.

It is known to illuminate planar chromatography or thin-layerchromatography supports with ultraviolet (UV) radiation and to acquire,using a video camera, images of these supports which are renderedfluorescent. This technique has many drawbacks.

The distance between the chromatography plate and the sensor isdetermined by the optical characteristics (focusing, focal length, etc.)of the objective used. The apparatuses of the known type are bulky.

The low resolution and limited surface area of the sensors of the CCD(charge-coupled device) type, in particular the sensor having a 0.85 mm(⅓ of an inch) diagonal limits the definition of the image to typically732×580 picture elements or pixels.

The apparatuses of the known type have a high manufacturing cost,especially because they use a large darkroom for illumination and imageacquisition and because the video cameras used correspond tonon-standardized professional equipment.

In addition, the apparatuses of the known type are not easy to handle;after having cut the UV source the darkroom must be opened in order toremove the treated chromatography plate, in order to replace it with thenext chromatography plate, and the darkroom must be closed again beforebeing able to turn the UV source on for the next acquisition.

It is consequently an object of the present invention to provide anapparatus for the acquisition, by fluorescence, of high-definitionimages of a plane or substantially plane support.

It is also an object of the present invention to provide such anapparatus which is very reliable.

It is also an object of the present invention to provide such anapparatus which does not present a hazard for an operator.

It is also an object of the present invention to provide such anapparatus which is compact.

It is also an object of the present invention to provide a rapid imageacquisition apparatus.

It is also an object of the present invention to provide an imageacquisition apparatus which is easy to use.

It is also an object of the present invention to provide an automaticimage acquisition system capable of processing a plurality ofchromatography supports autonomously.

It is also an object of the present invention to provide such anapparatus or such a system at a moderate manufacturing cost.

These objectives are achieved by an image acquisition apparatusaccording to the present invention, which comprises a UV radiationsource capable of making the supports, the image of which it is desiredto acquire, fluorescent, a window transparent to UV and to visiblelight, typically rectangular, for housing a support for the image to beacquired, a linear sensor, the length of which is preferablyapproximately equal to the width of the window for housing a support,and means for driving the sensor and, preferably, the UV radiationsource parallel to one of the edges of the window for housing an imagesupport.

The subject of the invention is mainly an apparatus for the acquisitionof fluorescent images of a plane object, comprising means for housingthe plane object whose image it is desired to acquire, a UV radiationsource inducing the photoluminescence of said object and a sensorsensitive to the fluorescent radiation, characterized in that itincludes a carriage which supports a linear sensor provided with aplurality of aligned photosites and means for driving the carriage whichsupports the linear sensor with respect to the region of the objectwhose image it is desired to acquire and control means for controllingthe illumination with UV radiation and for moving the carriage withrespect to the object, with the acquisition of a succession of imagelines corresponding to at least one region of the plane object whoseimage it is desired to acquire.

The subject of the invention is also an image acquisition apparatus,characterized in that said apparatus is a flat digitizer with means forholding the object stationary and for moving the carriage.

The subject of the invention is also an apparatus characterized in thatthe carriage furthermore includes at least one UV radiation source.

The invention also has [sic] an apparatus characterized in that the UVradiation source is a linear source placed parallel to the linearsensor.

The subject of the invention is also an apparatus, characterized in thatit includes a window without a pane and corresponding to the acquisitionregion scanned by the carriage.

The subject of the invention is also an apparatus, characterized in thatit includes a window corresponding to the acquisition region of theobject, provided with a pane made of a material transparent to thefluorescent visible radiation and to the radiation inducing thephotoluminescence.

The subject of the invention is also an apparatus, characterized in thatit includes multiple UV radiation sources corresponding to several UVradiation wavelengths.

The subject of the invention is also an apparatus, characterized in thatit includes a cover provided with means for automatically stopping theemission of UV radiation if the cover is not properly closed.

The subject of the invention is also an apparatus, characterized in thatit includes a charger ensuring that the image acquisition window isautomatically supplied with a rigid chromatography plate.

The subject of the invention is also a system for the processing offluorescent planar-chromatography images, characterized in that itincludes an apparatus according to the invention combined with acomputer provided with image processing software.

The invention will be more clearly understood by means of thedescription below and the appended figures given as non-limitingexamples, in which:

FIG. 1 is a schematic cross-sectional view of an image acquisitiondevice of a known type;

FIG. 2 is a schematic perspective view of the preferred embodiment of anapparatus according to the present invention;

FIG. 3 is a perspective view of an embodiment of a carriage used in theapparatus of FIG. 2;

FIG. 4 is a schematic cross-sectional view in a vertical plane of anembodiment of an apparatus according to the present invention providedwith an automatic charger.

In FIGS. 1 to 4, the same reference numbers have been used to denote thesame components.

FIG. 1 shows an embodiment of an apparatus of known type for theacquisition of fluorescent images of a chromatography plate 1,comprising an enclosure 3 impermeable to visible light and to UVradiation, a support 5 for the chromatography plate 1, an illuminationdevice 7, comprising one or more UV radiation sources, which is directedtoward the support 5 and a video camera 9. The camera 9 typically has afixed-focus objective 11 or a zoom, ensuring the formation of an imageon a sensor 13 of the charge-coupled type. The image obtained by thecamera 9 is processed by digital processing means, typically amicrocomputer. The output of the camera 9 is connected to ananalog-to-digital converter 15 which may be incorporated into theacquisition apparatus, may form an independent electronic unit or may beincorporated into an acquisition card of a computer.

The dimensions of the enclosure 3 forming the darkroom are mainlydetermined by the distance separating the objective 11 from the focalplane corresponding to the support 1, determined by the characteristicsof the camera 9 and especially by the focal length of the objective, bythe focusing carried out and especially by the distance between theobjective and the plane of the video sensor 13. Apart from theabovementioned drawbacks relating to the bulk, the low definition of theimages provided by the camera 9 and the handling problem, the apparatusin FIG. 1 must be provided with a powerful UV source 7 capable ofuniformly illuminating, simultaneously, the entire surface of the plate1.

The apparatus according to the present invention can be easily producedfrom available standard components or, advantageously, as illustrated inFIG. 2, can be made by modifying a digitizer (or scanner) intended foroffice automation and/or graphical artwork. The apparatus 17 accordingto the present invention includes a carriage 19 capable, upon command,of moving past a window 21 for housing an image support, such as a rigidchromatography plate or a flexible support. The carriage 19 is driven bydriving means 23, typically an electric stepper motor driving a coggedendless belt. The carriage 19 is guided by one or preferably two guiderails 27 placed parallel to the longitudinal edge 25 of the window 21.The rail 27 is made from folded sheet or, advantageously, consists of ametal section, for example a cylindrical section. The carriage 19supports, on the one hand, one or more UV radiation sources 29 and, onthe other hand, a linear video sensor 31, typically a linear array ofcharge-coupled devices extending over the entire width of the window 21.Likewise, the sources 29 advantageously extend parallel to the sensor 31over the entire width of the window 21. As a variant, the UV radiationsources 29 are stationary. The sources 29 and the video sensor 31 may beassociated with optical components, such as lenses, especiallycylindrical lenses, or return mirrors. It is essential that the window21 allow transmission of the radiation for illuminating the support,especially a chromatography plate, coming from the sources 29 andpropagation of this light coming, by reflection or fluorescence, fromthe support 1 onto the sensor 31. Thus, the window 21 may have no pane,the support being formed by the longitudinal rim 25 and/or a transverserim 28 and/or by a frame placed on these rims in the case of achromatography plate having dimensions smaller than those of the window21. On the other hand, the window 21 may be provided with a windowtransparent to the wavelengths used, especially to UV radiation and tovisible light. It is possible, for example, to use a pane made of quartzor of plastic transparent to visible and UV radiation. The carriage 19is connected via a cable 30, for example a ribbon cable, to anelectronic card 32 for controlling the components of the digitizer, forshaping the signals, especially sampling, for example over 24, 30 oradvantageously 36 bits (8, 10 or 12 bits per primary color), and forcommunicating with an external machine 33, for example with amicrocomputer provided with a parallel or SCSI interface card, theinterface card being connected to the scanner via a cable 35.Advantageously, an image is transmitted to the computer without reducingthe dynamic range of the images coded, for example, over 24, 30 or 36bits. The carriage 19 furthermore includes means for switching the lightsources 29 and the video sensor 31, as well as means 37 for mechanicalcoupling to the rails 27, for example bushes in the case of cylindricalrails and means for coupling to the drive belt. The cover 39, opaque tovisible light and to UV radiation protects the video sensor 31 from anyspurious light getting in, and simultaneously protects the operatoragainst irradiation by the UV radiation. Advantageously, the cover 39 isprovided with means 41 for turning the sources 29 off should the coverbe opened. For example, the cover is provided with a conducting element41 which ensures, when the cover is closed, that there is electricalcontinuity between terminals 43 placed in the body of the digitizer 17and connected in series with the electrical supply source 29. Thus,accidental opening of the cover 39 instantly stops the emission of UVlight toward the operator and thus prevents him from being irradiated byradiation which could prove to be hazardous to his health.

The carriage 19 includes, for example, a source 29, capable of emittingUV radiation at 254 nm, a source 29 capable of emitting UV radiation ata wavelength of 365 nm, or a UV source which can be tuned to these twofrequencies, together with a source of visible light. Of course, the useof radiation having other wavelengths does not lie outside the scope ofthe present invention. The video sensor 31 has, for example, 2587photosites distributed over a length of 219 mm corresponding to aresolution of 300 dots per inch or 5174 photosites distributed over 219mm, corresponding to a resolution of 600 dots per inch, or 10 348photosites distributed over 219 nm, corresponding to a resolution of1200 dots per inch.

The carriage 19, the guiding means 27 and 37, and/or the drive means,such as the motor 23 or the cogged belt, may advantageously bestrengthened so as to withstand the weight of the additional lightsource without any loss of precision in the movement of the carriage,typically between 76.2 dots per mm (300 dots per inch), 152 dots per mm(corresponding to 154.4 dots per inch), 304.8 dots per mm (correspondingto 1200 dots per inch) or 609.6 dots per mm (corresponding to 2400 dotsper inch).

In the preferred embodiment, the digitizer 17 is a flat digitizer.However, the use of other digitizer types such as, for example, runningdigitizers or digitizers for slides, in which one or more sources 29would be placed on one side of the video sensor, is not outside thescope of the present invention. Likewise, it is possible to adapt a flatscanner with a slide holder, such as the scanners sold under the nameDUOSCAN by the company AGFA in order for chromatography plates to bedigitized according to the present invention. In this case too, thesources 29 are placed on the same side as the video sensor. The lattertype of scanner has the advantage of not requiring a pane made of UVtransparent material, while still ensuring that the mechanism of thedigitizer is protected from dust.

FIG. 4 shows an alternative embodiment of an apparatus according to thepresent invention, provided with an automatic charger for charging withrigid chromatography plates 1. The apparatus 17 is provided, on the onehand, with a magazine 45 for housing a stack of plates resting on anumber of rollers 47, at least one of which is motorized. The rollers 47are placed opposite a slot 49 for housing the support 1 in the apparatus17. The window 21 is also provided with rollers 47 for ejecting adigitized plate into a magazine 51 located, for example, beneath a slot53 for ejecting the processed chromatography plates 1 placed oppositethe slot 49.

The picture-taking apparatus 17 according to the present inventionoperates in the following manner:

A conventional planar chromatography plate is placed in front of thewindow 21, especially on the rims 25 and 28, or in the magazine 45. Inthe latter case, a logic command issued by the computer 33 makes theplate move past the window 21. The plate may include, in addition to achromatography support of known type, identification means, such as abar code or, advantageously, characters identifiable by opticalcharacter recognition. The characters are advantageously printed in aneasily identifiable font, such as ROC B. Thus, the high definition ofthe image acquired by the apparatus 17 according to the presentinvention can be used to achieve one-to-one correspondence betweenacquired images and controls corresponding to specimens processed bychromatography.

The cover 39 is closed again. The apparatus 17 receives a command fromthe computer 33, a factory-programmed command or a command entered via akeyboard (not shown) of the apparatus. This command corresponds toturning a light source 29 on and to scanning the surface of the plate 1with successive acquisition of all the lines of the image which issimultaneously transmitted to the computer 33. The scanning can then becarried out at a different frequency (UV or visible) so as, in thelatter case, to detect colored molecules directly or after the action ofa more or less specific developer. The fluorescence allows the detectionof directly fluorescent molecules or the reading of fluorescenceinhibition of a plate containing a fluorescence indicator. The imagesacquired are advantageously stored in a conventional bulk memory, forexample a hard disk of the computer 33 which carries out the processingaccording to the strict rules of “good laboratory practice”, so as toobtain qualitative and quantitative results of spots likely to bepresent on the plate 1. A software package sold under the name BORWIN bythe company JMBS may, for example, be used. This software package may besupplemented with a software package for optical character recognitionor for reading bar codes. The identified characters or the decoded codeis [sic] associated, in the form of references, comments or filenames,with the processed images.

The apparatus according to the present invention makes it possible toimprove the precision of the processing insofar as it provides the imageprocessing software with a high-definition image comprising, forexample, 4724 dots by 4724 dots (for a digitizer resolution of 600 dotsper inch) or a definition of 9448 dots by 9448 dots for a definition of1200 dots per inch, or for plates having sides of 20 cm.

The present invention is not limited to chromatography, but applies toall types of acquisition of high-definition fluorescent images.Likewise, it may replace or complement the video sensor with a sensorwhich is sensitive to UV or other radiation.

The present invention applies mainly to image acquisition correspondingto the revelation of a chemical or physical phenomenon.

The present invention applies mainly to planar chromatography orthin-layer chromatography.

1. Apparatus for the acquisition of fluorescent images of a planeobject, comprising means for housing the plane object whose image it isdesired to acquire, a UV radiation source inducing photoluminescence ofsaid object and a sensor sensitive to fluorescent radiation,characterized in that it includes a carriage which supports a linearsensor provided with a plurality of aligned photosites, at least one UVradiation source and means for driving the carriage which supports thelinear sensor with respect to a region of the object whose image it isdesired to acquire and control means for controlling illumination withUV radiation and for moving the carriage with respect to the object,with the acquisition of a succession of image lines corresponding to atleast one region of the plane object whose image it is desired toacquire, characterized in that it includes a cover provided with meansfor automatically stopping the emission of UV radiation if the cover isnot properly closed.
 2. Apparatus according to claim 1, characterized inthat said apparatus is a flat digitizer with means for holding theobject stationary and for moving the carriage.
 3. Apparatus according toclaim 1, characterized in that the UV radiation source is a linearsource placed parallel to the linear sensor.
 4. Apparatus according toclaim 1, characterized in that it includes a window without a pane andcorresponding to an acquisition region scanned by the carriage. 5.Apparatus according to claim 1, characterized in that it includes awindow corresponding to an acquisition region of the object, providedwith a pane made of a material transparent to fluorescent visibleradiation and to radiation inducing photoluminescence.
 6. Apparatusaccording to claim 1, characterized in that it includes multiple UVradiation sources corresponding to several UV radiation wavelengths. 7.Apparatus according to claim 1, characterized in that it includes acharger ensuring that an image acquisition window is automaticallysupplied with a rigid chromatography plate.
 8. Apparatus for theacquisition of fluorescent images of a plane object, comprising meansfor housing the plane object whose image it is desired to acquire, a UVradiation source inducing photoluminescence of said object and a sensorsensitive to fluorescent radiation, characterized in that it includes acarriage which supports a linear sensor provided with a plurality ofaligned photosites, with at least one UV radiation source for emittingradiation at two wavelengths in order to carry out a chromatographicanalysis for detection of directly fluorescent chemical substances anddetection by a fluorescence inhibition method, at least one UV radiationsource and means for driving the carriage which supports the linearsensor with respect to a region of the object whose image it is desiredto acquire and control means for controlling illumination with UVradiation and for moving the carriage with respect to the object, withthe acquisition of a succession of image lines corresponding to at leastone region of the plane object whose image it is desired to acquire,characterized in that it includes a cover provided with means forautomatically stopping the emission of UV radiation if the cover is notproperly closed.
 9. System for the processing of fluorescentplanar-chromatography images, characterized in that it includes anapparatus comprising means for housing the plane object whose image itis desired to acquire, a UV radiation source inducing photoluminescenceof said object and a sensor sensitive to fluorescent radiation,characterized in that it includes a carriage which supports a linearsensor provided with a plurality of aligned photosites, at least one UVradiation source and means for driving the carriage which supports thelinear sensor with respect to a region of the object whose image it isdesired to acquire and control means for controlling illumination withUV radiation and for moving the carriage with respect to the object,with the acquisition of a succession of image lines corresponding to atleast one region of the plane object whose image it is desired toacquire, characterized in that it includes a cover provided with meansfor automatically stopping the emission of UV radiation if the cover isnot properly closed, combined with a computer provided with imageprocessing software.